Grinding machines typically use grinding or sanding belts to grind a workpiece. During the grinding operation, the grinding belt picks up and accumulates grinding dust, which has to be removed if the grinding belt is to maintain its effectiveness over a relatively long period. To this end, it is known in a belt type grinding machine to provide an air supplying nozzle arrangement with outlet holes through which fine air jets are supplied. The outlet holes are placed near the location where the grinding belt comes into contact with the workpiece to be ground. The fine air jets from the nozzle arrangement are directed onto the grinding belt to dislodge and move any accumulated grinding dust off the grinding belt. To be as effective as possible with acceptable air consumption, the air jets are spaced linearly along the width of the grinding belt. To be able to clean the grinding belt uninterruptedly over the entire width, the nozzle arrangement is oscillated along the grinding belt width.
It is known to use a pneumatic oscillating drive having a piston of a double-action cylinder to oscillate the nozzle arrangement at a frequency of from 2 to 4 Hz and a stroke of approximately 40-60 mm. This movement is transmitted via pistons to the nozzle arrangement mounted for movement in guide rollers or bearings. This nozzle arrangement is oscillated over the width of the grinding belt.
The shortcoming of this type of blowing device is that the roller/bearing assembly required to hold and guide the nozzle assembly is expensive and is prone to wear. Furthermore, the nozzle arrangement is also subjected to wear. Thus, there is a need for a blowing device or nozzle arrangement that reduces or eliminates these problems.
The present invention fulfills this need.